<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>‘</title>
</head>
<body>
<table id="tbl">
    <tr>
        <td>年龄</td>
        <td>性别</td>
        <td>姓名</td>
        <td>段位</td></tr>

</table>
<button onclick="add">添加</button>
<form id="ff" style="display:none">
    <input type="text" name="uname">
    <input type="button" name="确定" onclick="addtr()">
</form>

<script>
    var tbl=document.getElementById('tbl');
    var str=`<tr>
        <td>年龄</td>
        <td>性别</td>
        <td>姓名</td>
        <td>段位</td></tr>`
    tbl.innerHTML+="str";
    function add(){
        var ff=document.getElementById('ff');
        ff.style.display='block';

    }
    function addtr(){
        var ff=document.getElementById('ff');/*ff:表单*/

    }
</script>
</body>
</html>